How do you convert units of nitrogen?

Question

If I have a 40lb cylinder of nitrogen (regular compressed nitrogen gas) @2000psi and I send it into a 60 gallon tank, how much psi will I have in the tank?

Answer 1

As I understand compressed gas cylinder standards, a "40 lb" cylinder has the capacity to hold 40 pounds of water. Since water has a density of 8.33 lb/gal, the volume of the cylinder is 4.8 gallons. Gases obey the law P1V1 = P2V2, so substituting,

(4.8 gal) (2000 psi) = (60 gal) P2,

P2 = 160 psi.

Note that this would be true no matter what the gas is.